‘Friends in high places, ma’am?’ Gillard asked.

‘The very pinnacle, Craig.’ She winked, and walked out.

Back at the incident room Gillard pulled out Ordnance Survey maps of Surrey, and using the largest available table spread them out. He called over DI Claire Mulholland, and they laid over some clear acetate so they could begin with marker pens noting the various events. They concentrated on the River Wey upstream from Lacey Dutton towards Hampshire. It was a good fifteen miles south-west of Westmeare and at least ten south of Godalming. Clandon was even further away.

‘We’ve not got much here,’ Gillard said. ‘There are ANPR cameras on the A281 and A283, and there is a road safety camera on Loxcombe Bridge at the traffic lights. I think the best we can do for now is to try to see if anyone who has been in the vicinity of Westmeare on Sunday night has also been in and around Lacey Dutton in the last few days.’

‘Whoever is clever enough to have constructed that girl on the train costume drama would certainly be smart enough not to get caught using the same vehicle in those two locations,’ Claire said.

‘I agree. But what else do we have?’ Gillard asked. ‘The DNA tests on the railway seat cushion came back with half a dozen different traces, one animal, almost certainly dog.’

‘Why dog?’

‘British Transport Police warned me to expect that on any DNA test of a train seat. It’s from what passengers have walked in before they put their feet on the seat opposite.’

‘Icky.’

‘Yes. Anyway, none of the human traces are on the national database. We don’t even seem to have a trace for Beatrice on it, even though the impostor was sitting there wearing her coat.’

Down the far end of the incident room, they could hear chuckling. Rainy Macintosh and Carl Hoskins were watching something that amused them. Gillard wandered over, feeling that he could do with a little light relief.

‘You got to see this, sir.’ Hoskins beckoned Gillard over to his computer terminal. Macintosh discreetly slipped away, returning to do some work.

‘What is it?’

‘CCTV from last Monday’s Woking carjacking. I’m calling it the tale of the flying slipper.’

‘I’m due in a meeting in two minutes,’ Gillard said. He wasn’t looking forward to it. The German minister and his wife were already waiting in Rigby’s office.

‘You’ll only need half that, sir.’

Hoskins sat his boss in the chair, and restarted the footage again on quarter speed slo-mo.

It was domestic CCTV footage taken from above the front door of a house looking out across its short drive and onto a residential street. A dark Mitsubishi Warrior, an off-road monster pick-up with high suspension and a snorkel, reversed into the picture from the right-hand side close to the camera and swung in a fast clockwise arc down the drive towards the street. For the first one or two seconds nothing whatever could be seen of the occupant. However, a motion-sensor light further off to the left was triggered, and for a few seconds the car was bathed in dazzling light.